One can never have too many clamps. These are the kind that I use and they work just fine.
http://www2.towerhobbies.com/cgi-bin...&I=LXK854&P=ML
Also, I use wooden clothes pins. Take them apart and reverse the spring so that the flat ends are squeezed together. These also make ideal clamps for holding flat thin stuff together. A bag of wood clothes pins is cheap!
Phil